We’ve got a hybrid setup where the front-end is a React app handling the implicit grant flow, and we need to validate that the JWT is still good before hitting our internal APIs. The token comes back fine from the authorize endpoint, but when we try to use it downstream, things get messy.
I’m trying to validate the token payload locally in the browser before sending requests to Genesys Cloud. The goal is to avoid unnecessary 401s. Here’s the validation logic I wrote:
const validateToken = (token) => {
try {
const payload = JSON.parse(atob(token.split('.')[1]));
const expiry = payload.exp * 1000;
const now = Date.now();
console.log('Token expires at:', new Date(expiry));
console.log('Current time:', new Date(now));
return expiry > now;
} catch (e) {
return false;
}
};
The logs show the expiry is in the future. The token looks valid. But when I make a fetch request to /api/v2/users/me with that token in the Authorization header, I get a 401 Unauthorized.
POST https://api.mypurecloud.com/api/v2/users/me 401 (Unauthorized)
I’ve checked the header format:
Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...
It looks correct. The tenant ID matches what we’re using in Postman, where the same token works fine if I grab it from the URL fragment immediately after login. Wait, Postman doesn’t use implicit grant usually. We’re using PKCE in the new build but stuck with implicit for this legacy module.
Is there something specific about the implicit grant tokens that makes them invalid for the API gateway immediately? Or is the clock skew on the server side? We’re in Sydney, so maybe the server time is off? No, that usually gives a different error.
Also, I noticed the aud claim is https://api.mypurecloud.com. That matches. The iss is also correct.
I’ve tried refreshing the token, but the refresh token isn’t returned in the implicit flow. So I’m stuck. If the token is expired, I have to redirect to login again, which is annoying for the user.
What am I missing in the validation step?